This invention relates to vacuum cleaners.
Vacuum cleaners, especially vacuum cleaners for domestic as opposed to industrial use are frequently classified into two groups, namely, so-called upright cleaners and cylinder cleaners. Upright cleaners which, apart from the possible addition of optional accessories, may be regarded as self contained units in the sense that, all components, such as a motorized fan/suction unit, suction head, dust collecting reservoir, handle and all controls are housed within or on a single wheeled or otherwise manually displaceable unit. On the other hand, a hand held and controlled suction head in a cylinder cleaner is connectable via a flexible hose to a wheeled or otherwise displaceable unit which houses all moving and driven components such as a motorized fan/suction unit and, usually, a dust collecting reservoir. In the cleaners of each group, the dust collecting reservoir is customarily fitted with an air-permeable dust collecting bag which can be emptied and re-used, or include means for housing a disposable air-permeable dust collecting bag.
Although specific reference will be made in the following disclosure to upright vacuum cleaners, the concept of the present invention may also be applied to cylinder cleaners as well as vacuum cleaners for industrial and commercial use. Vacuum cleaners for industrial use are normally constructed similar to cylinder cleaners but, having regard to the environment in which they are required to operate, they are much heavier and more robust machines.
Upright vacuum cleaners conventionally include an impact imparting element which serves to disturb or release dust, etc., from a surface being cleaned so that it may be more easily sucked into the cleaner through a vacuum such dust and dirt or suction nozzle. The impact imparting element takes different forms including a rotatable brush or beater.
A partial vacuum is established at the vacuum or suction nozzle by the motorized fan which also serves to blow or suck air through a filter and the dust collector bag.
The air is led to an inlet for the fan through a relatively narrow nozzle which thus creates the partial vacuum in the cleaner. Usually, power for the beater is taken from a pulley on the fan motor shaft via a drive belt. This arrangement has several inherent disadvantages. The use of pulleys to drive the beater limits the choice of possible physical arrangements for the fan motor and beater. The belt is often vulnerable to damage. In addition, it is useful to be able to stop the motion of the beater when the vacuum cleaner is stationary to reduce wear on, for example, being cleaned, a carpet. This is not easily achieved in a conventional belt driven system.